People who lash out and kill an abusive family member should be able to better defend themselves in court, a new report into family violence suggests.

Agencies must better heed the red flags of family violence homicides including non-fatal choking and the victim separating from the offender, the report by the Family Violence Death Review Committee, made public today, says.

The findings reveal 139 people, mostly women, died from family violence and family violence-related homicides between 2009 and 2012. It called for a stronger collective response from police, the justice system, support services and the public to severe family violence.

"The committee believes the current family violence system over-relies on victims taking actions such as going to a women's refuge or taking out a protection order, and that the responsibility for keeping them safe should rest with support services and the community," co-author Julia Tolmie, a University of Auckland associate professor, said.

Also suggested is loosening the legal defence of self-defence for domestic violence victims, making it more accessible to people who kill their partners because of family violence.

The report also found, of the 63 victims killed by their partners, half of the deaths were when the abused had or were attempting to leave their abuser. Agencies such as police, the justice system, and social workers needed to understand how risky leaving was, Tolmie said.

"We keep thinking: ‘Why didn't she just leave?' and people don't realise separation is one of the most dangerous times."

The committee also recommends creating a separate offence for non-lethal choking, a form of violence it describes as a "red flag" for future abuse and death. In 12 of the 17 cases examined in depth, victims who were killed had previously reported being choked.

Choking is often prosecuted in New Zealand as a male-assaults-female charge.

"Judges and police . . . look at his history and see a minor assault, they won't see this is a person with very high risk of lethal homicide," Tolmie said.

Justice Minister Judith Collins said she had asked ministry officials to prepare advice on the report's conclusions, including making the defence of self-defence more accessible.

"We must be cautious to ensure that any new defences . . . don't excuse behaviour that the accused should be held accountable for," Collins said.

A new bill, passed this week, would allow victims to take out "non-contact" orders, preventing offenders from contacting victims in any form and could even prevent the offender living or working in a particular area.